Function dlink_add

lib_acl/src/stdlib/common/acl_dlink.c:219–434

}

static ACL_DITEM *dlink_add(ACL_ARRAY *a, acl_int64 begin, acl_int64 end)
{
	ACL_DITEM *pitem_right, *pitem_left, *pitem;
	int idx_begin, idx_end;
	int	ret;

	/* sanity check, maybe useless */
	/* because it's used internal */
	if(begin > end)
		return NULL;

	idx_begin = begin_pos(a, begin);
	if(idx_begin < 0 || idx_begin >= acl_array_size(a)) /* an error happened */
		return NULL;

	idx_end   = end_pos(a, end);
	if(idx_end < 0 || idx_end >= acl_array_size(a))	/* an error happened */
		return NULL;

	if(idx_begin > idx_end)	/* an error happened */
		return NULL;

	if(acl_array_size(a) == 0) {	/* the d-link is empty so just add one :) */
		pitem = dlink_append(a, begin, end);
		return pitem;
	}

	pitem_left  = (ACL_DITEM *) acl_array_index(a, idx_begin);
	pitem_right = (ACL_DITEM *) acl_array_index(a, idx_end);

	/* if idx_end == 0 then idx_begin must be equal to 0, I'm sure it :) */
	if (idx_begin == idx_end) {
		/*
		 * pitem_left == pitem_right
		 * here idx_begin maybe one of: 0, a->count - 1,
		 * or the one between 0 and a->count
		 * this is to say the begin and end is on the same d-link
		 */

		if (end + 1 < pitem_left->begin) {
			/*
			 * here idx_begin == idx_end must be equal to 0
			 * the begin and the end must be less
			 * than the next node's begin
			 * add one new node before the one
			 */
			pitem = dlink_prepend(a, begin, end);
			return pitem;
		}

		if (begin > pitem_left->end + 1) {
			/*
			 * this is to say begin and end
			 * between the current node's end
			 * the next node's begin, and we just
			 * insert one new node between the
			 * current node and the next node, when
			 * the next node is NULL(which say that